1. Field of the Invention
The present invention relates to an illuminating apparatus capable of varying a light intensity distribution in a plane and a display apparatus using the illuminating apparatus.
2. Description of the Related Art
For example, as a light source of a backlight of a liquid crystal display apparatus, a light source using a stick-shaped fluorescent tube such as CCFL (Cold Cathode Fluorescent Lamp), EEFL (External Electrodes Fluorescent Lamp), or HCFL (Hot Cathode Fluorescent Lamp) is conventionally known. A backlight using a stick-shaped ultraviolet lamp as a light source, converting ultraviolet light to visible light, using the visible light as illumination light is also proposed (refer to Japanese Unexamined Patent Application Publication No. 2001-266605).
Recently, a partial-drive-type backlight is developed in which a number of point light sources such as LEDs (Light Emitting Diodes) are used as a light source, a light emission plane is divided in a plurality of partial light emission regions, and light emission control is performed in the partial light emission regions independently of each other. A liquid crystal display apparatus using the backlight of the partial-drive-type is developed. In the liquid crystal display apparatus, light intensity of the backlight is partially changed according to a video image to be displayed, so that the light intensity reproduction range (dynamic range) exceeding the limit contrast ratio in liquid crystal display is realized. One of concrete methods is a method of reducing light intensity of black by partially reducing (turning off) the background light of a portion of displaying a dark image. The technique is commonly called local dimming.